Refrigerator using non-azeotropic refrigerant mixture and control method thereof

ABSTRACT

A refrigerator using a non-azeotropic refrigerant mixture (NARM) and a control method thereof. The refrigerator reduces the rotational speed of a freezing chamber fan or stopping the freezing chamber fan for a designated time, and/or increasing the rotational speed of a compressor in a simultaneous freezing/refrigerating operation mode of an NARM cycle as compared to a freezing operation mode, and may thus decrease evaporation latent heat of a refrigerant consumed by a freezing chamber evaporator and relatively increase evaporation latent heat of the refrigerant usable in a refrigerating chamber evaporator without increase in a charging amount of the refrigerant, thereby preventing over-charging due to increase in the charging amount of the refrigerant and reducing cycling loss.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean PatentApplication No. 10-2011-0115911, filed on Nov. 8, 2011 in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a refrigerator using anon-azeotropic refrigerant mixture (NARM) and a control method thereof.

2. Description of the Related Art

Non-azeotropic refrigerant mixtures (NARMs) are refrigerants, thetemperature of which is changed during a phase change processdifferently from pure refrigerants generally used in refrigerators.

Efficiency of a refrigerator may be improved by applying such anon-azeotropic refrigerant to a refrigerant cycle.

If the non-azeotropic refrigerant is used, a refrigerant temperature ata point where evaporation is started becomes lower than the meanevaporation temperature. By applying such a fact to operation of afreezing chamber, the mean evaporation temperature may be raised ascompared to a pure refrigerant, and thus a compression ratio may bereduced. For this reason, a refrigerator using an NARM cycle isconfigured such that the refrigerant first passes through a freezingchamber evaporator and then passes through a refrigerating chamberevaporator differently from a general refrigerator.

Therefore, a refrigerant charging amount may be increased compared tothat of a conventional refrigerant cycle and a refrigerating chamberevaporator may be installed at a position further upstream than afreezing chamber evaporator.

In the conventional refrigerant cycle, the refrigerating chamberevaporator first uses evaporation latent heat of a refrigerant and thenthe freezing chamber evaporator uses remaining latent heat duringsimultaneous freezing/refrigerating operation. Here, althoughevaporation latent heat of the refrigerant usable in the freezingchamber evaporator is sufficient, freezing chamber heat load issupplemented in an independent freezing operation mode and thusoperation of the cycle is not hindered.

However, in case of such a serial NARM cycle, the freezing chamberevaporator is installed at a position further upstream than therefrigerating chamber evaporator and thus the refrigerating chamberevaporator uses evaporation latent heat remaining after use in thefreezing chamber evaporator. Since cooling operation of therefrigerating chamber needs to be finished in the simultaneousfreezing/refrigerating operation mode (because there is no independentrefrigerating operation mode in the conventional refrigerant cycle),evaporation latent heat remaining after use in the freezing chamberevaporator needs to be sufficient to perform the cooling operation ofthe refrigerating chamber.

For this reason, the charging amount of the refrigerant in the NARMcycle is increased. Increase in the charging amount of the refrigerantcauses overcharge of the refrigerant during independent freezingoperation, thus producing side effects, such as lowering of systemefficiency. Because over-charging of the refrigerant at an amount morethan a proper level causes increase of input of the compressor and riseof an evaporation temperature due to increase in the operating pressureof the cycle.

Further, increase in the charging amount of the refrigerant serves toincrease loss generated by ON/OFF operation of the refrigerator. Suchloss is referred to as cycling loss, and is generated in a refrigeratorsystem in which the ON/OFF operation of the refrigerator is continuouslyperformed. However, the cycling loss tends to increase together withincrease in the charging amount of the refrigerant. The cycling loss maybe divided into migration loss generated due to transfer of ahigh-pressure refrigerant distributed at a high-pressure side to alow-pressure side when a compressor is turned off, and redistributionloss to reach again a stable cycle operation state by transferring apart of the refrigerant located at the low-pressure side to thehigh-pressure side when the compressor is turned on, and both lossesincrease also together with increase in the charging amount of therefrigerant.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide arefrigerator using a non-azeotropic refrigerant mixture (NARM) whichincreases evaporation latent heat usable in a refrigerating chamberevaporator during simultaneous freezing/refrigerating operation withoutincrease in the charging amount of a refrigerant in a NARM cycle, and acontrol method of the refrigerator.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

In accordance with an aspect of the present disclosure, a refrigeratorincludes a freezing chamber and a refrigerating chamber, a compressor tocompress a refrigerant, a condenser to cool the refrigerant dischargedfrom the compressor, a refrigerating chamber evaporator to cool therefrigerating chamber, a freezing chamber evaporator provided betweenthe condenser and the refrigerating chamber evaporator at a positionfurther upstream than the refrigerating chamber evaporator and to coolthe freezing chamber, a freezing chamber fan blowing cool air havingundergone heat exchange in the freezing chamber evaporator, and acontroller to control operation of the compressor and the freezingchamber fan, wherein the controller changes the rotational speed of atleast one of the freezing chamber fan and the compressor so as toincrease the amount of the refrigerant introduced into the refrigeratingchamber evaporator in a simultaneous freezing/refrigerating operationmode.

The controller may lower the rotational speed of the freezing chamberfan in the simultaneous freezing/refrigerating operation mode ascompared to a freezing operation mode.

The controller may temporarily lower the rotational speed of thefreezing chamber fan to 0 in the simultaneous freezing/refrigeratingoperation mode.

The controller may increase the rotational speed of the compressor inthe simultaneous freezing/refrigerating operation mode as compared to afreezing operation mode.

The controller may lower the rotational speed of the freezing chamberfan in the simultaneous freezing/refrigerating operation mode ascompared to a freezing operation mode or temporarily stop the operationof the freezing chamber fan in the simultaneous freezing/refrigeratingoperation mode, and may increase the rotational speed of the compressorin the simultaneous freezing/refrigerating operation mode as compared tothe freezing operation mode.

In accordance with another aspect of the present disclosure, a controlmethod of a refrigerator in which a freezing chamber evaporator isprovided at a position further upstream than the refrigerating chamberevaporator includes determining whether or not the refrigerator is in asimultaneous freezing/refrigerating operation mode, and changing therotational speed of at least one of a freezing chamber fan and acompressor so as to increase the amount of a refrigerant introduced intothe refrigerating chamber evaporator, upon determining that therefrigerator is in the simultaneous freezing/refrigerating operationmode.

The change of the rotational speed of at least one of the freezingchamber fan and the compressor may include lowering the rotational speedof the freezing chamber fan in the simultaneous freezing/refrigeratingoperation mode as compared to a freezing operation mode.

The change of the rotational speed of at least one of the freezingchamber fan and the compressor may include temporarily lowering therotational speed of the freezing chamber fan to 0 in the simultaneousfreezing/refrigerating operation mode.

The change of the rotational speed of at least one of the freezingchamber fan and the compressor may include increasing the rotationalspeed of the compressor in the simultaneous freezing/refrigeratingoperation mode as compared to a freezing operation mode.

The change of the rotational speed of at least one of the freezingchamber fan and the compressor may include lowering the rotational speedof the freezing chamber fan in the simultaneous freezing/refrigeratingoperation mode as compared to a freezing operation mode or temporarilystopping the operation of the freezing chamber fan in the simultaneousfreezing/refrigerating operation mode, increasing the rotational speedof the compressor in the simultaneous freezing/refrigerating operationmode as compared to the freezing operation mode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent andmore readily appreciated from the following description of embodiments,taken in conjunction with the accompanying drawings of which:

FIG. 1 is a longitudinal-sectional view of a refrigerator in accordancewith an embodiment of the present disclosure;

FIG. 2 is a circuit diagram illustrating a non-azeotropic refrigerantmixture (NARM) cycle of the refrigerator in accordance with anembodiment of the present disclosure;

FIG. 3 is a control block diagram of the refrigerator in accordance withan embodiment of the present disclosure;

FIG. 4 is a timing diagram illustrating rotational speed change of afreezing chamber fan in a freezing operation mode and a simultaneousfreezing/refrigerating operation mode of the refrigerator in accordancewith an embodiment of the present disclosure;

FIG. 5 is a timing diagram illustrating rotational speed change of acompressor in the freezing operation mode and the simultaneousfreezing/refrigerating operation mode of the refrigerator in accordancewith an embodiment of the present disclosure;

FIG. 6 is a flowchart illustrating a control method of a refrigerator inaccordance with an embodiment of the present disclosure; and

FIG. 7 is a flowchart illustrating a control method of a refrigerator inaccordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like componentsthroughout.

FIG. 1 is a longitudinal-sectional view of a refrigerator in accordancewith an embodiment of the present disclosure.

As shown in FIG. 1, the refrigerator in accordance with an embodiment ofthe present disclosure includes a freezing chamber 12 located above adiaphragm 11 forming a part of a main body 10 and provided with theopened front surface, a freezing chamber door 13 opening or closing theopened front surface of the freezing chamber 12, a refrigerating chamber14 located under the diaphragm 11 and provided with the opened frontsurface, a refrigerating chamber door 15 opening or closing the openedfront surface of the refrigerating chamber 14, and a compressor 16provided at a rear portion of the lower portion of the main body 10.

A freezing chamber heat exchange device 30 and 31 and a refrigeratingchamber heat exchange device 40 and 41 performing heat exchange areprovided between the rear surface portions of the freezing chamber 12and the refrigerating chamber 14 and the main body 10, respectively.

A freezing chamber temperature sensor 17 and a refrigerating chambertemperature sensor 18 are provided at designated portions of the wallsof the freezing chamber 12 and the refrigerating chamber 14.

Shelves 19 and baskets 20 to store food are provided within the freezingchamber 12 and the refrigerating chamber 14.

A machinery chamber which is a separate space is provided at the rearportion of the lower portion of the main body 10, and the compressor 16and the condenser 50 are provided within the machinery chamber.

The freezing chamber heat exchange device 30 and 31 includes a freezingchamber evaporator 30 to cool air in the freezing chamber 12 throughheat exchange, and a freezing chamber fan 31 installed above thefreezing chamber evaporator 30 and circulating cool air having passedthrough the freezing chamber evaporator 30 to the inside of the freezingchamber 12.

A suction hole 32 through which air in the freezing chamber 12 is suckedby driving of the freezing chamber fan 31 is formed below the freezingchamber evaporator 30, and a plurality of discharge holes 33 touniformly discharge cool air blown by the freezing chamber fan 31 to theinside of the freezing chamber 12 is formed on the rear surface of thefreezing chamber 12.

Similar to the freezing chamber heat exchange device 30 and 31, therefrigerating chamber heat exchange device 40 and 41 includes arefrigerating chamber evaporator 40 to cool air in the refrigeratingchamber 14 through heat exchange, and a refrigerating chamber fan 41installed above the refrigerating chamber evaporator 40 and circulatingcool air having passed through the refrigerating chamber evaporator 40to the inside of the refrigerating chamber 14.

A suction channel 42 to suck air in the refrigerating chamber 14 bydriving of the refrigerating chamber fan 41 is provided below therefrigerating chamber evaporator 40, and a plurality of discharge holes43 to uniformly discharge cool air blown by the refrigerating chamberfan 41 to the inside of the refrigerating chamber 14 is formed on therear surface of the refrigerating chamber 14.

FIG. 2 is a view illustrating a non-azeotropic refrigerant mixture(NARM) cycle of the refrigerator in accordance with an embodiment of thepresent disclosure.

As shown in FIG. 2, the refrigerator having the NARM cycle includes thecompressor 16, a condenser 50, a capillary tube 60, the freezing chamberevaporator 30 and the refrigerating chamber evaporator 40, and thesecomponents are sequentially connected to refrigerant flow channelsrepresented by solid lines.

The capillary tube 60 is an example of an expansion device whichdecompresses and expands a refrigerant discharged from the condenser 50.

A condenser fan 51 which sucks air at the outside of the refrigeratorinto the condenser 50 and then discharges the air to the outside of therefrigerator so as to rapidly perform heat exchange with air at theoutside of the refrigerator is provided around the condenser 50.

A freezing chamber fan 31 which sucks air at the inside of the freezingchamber 12 into the freezing chamber evaporator 30 and then dischargesthe air to the inside of the freezing chamber 12 so as to rapidlyperform heat exchange with air at the inside of the freezing chamber 12is provided around the freezing chamber evaporator 30.

A refrigerating chamber fan 41 which sucks air at the inside of therefrigerating chamber 14 into the refrigerating chamber evaporator 40and then discharges the air to the inside of the refrigerating chamber14 so as to rapidly perform heat exchange with air at the inside of therefrigerating chamber 14 is provided around the refrigerating chamberevaporator 40.

Further, a 3-way valve 70, i.e., a flow channel switch valve toselectively change the respective refrigerant flow channels, is providedat an intersection of a refrigerant pipe connecting the freezing chamberevaporator 30 and the refrigerating chamber evaporator 40 and arefrigerant pipe connecting the freezing chamber evaporator and theinlet side of the compressor 16.

The NARM cycle having the above-described configuration is performed bycirculating a non-azeotropic refrigerant mixture (NARM) along thecomponents shown by arrows represented by dotted lines.

The temperature of the NARM is changed during a phase change processdifferently from pure refrigerants generally used in refrigerators. Thatis, the temperature of the NARM is raised as the NARM is evaporated.

In general, efficiency of a refrigerator cycle increases as acompression ratio between a high-pressure side and a low-pressure sideis reduced, and such a compression ratio is restricted by therefrigerant evaporation temperature of a freezing chamber evaporator.For example, if it is desired to keep the freezing chamber at atemperature of −20° C., the evaporation temperature needs to be lowerthan such a temperature and thus the temperature of the inside of thefreezing chamber acts as a critical point in decreasing the compressionratio.

If the NARM is used under this condition, the refrigerant temperature ata point where evaporation is started is lower than the mean evaporationtemperature, and thus, by applying the NARM to operation of the freezingchamber, the mean evaporation temperature may be raised as compared to apure refrigerant and a compression ratio may be reduced.

For this reason, the refrigerator using the NARM cycle is configuredsuch that the refrigerant first passes through the freezing chamberevaporator 30 and then passes through the refrigerating chamberevaporator 40 differently from a general refrigerator.

Therefore, in the NARM cycle, the freezing chamber evaporator 30 islocated at a position further upstream than the refrigerating chamberevaporator 40.

Now, the flow of the refrigerant in the NARM cycle will be described.The refrigerant discharged from the compressor 16 reaches the 3-wayvalve 70 via the condenser 50, the capillary tube 60 and the freezingchamber evaporator 30. The refrigerant pipe at the 3-way valve 70 isbranched so that the refrigerant having passed through the freezingchamber evaporator 30 is introduced into the inlet side of thecompressor 16 via the refrigerating chamber evaporator 40 or isintroduced directly into the compressor 16 bypassing the refrigeratingchamber evaporator 40 according to switching of the 3-way valve 70.

That is, according to switching of the 3-way valve 70, afreezing/refrigerating cycle in the order of the compressor 16, thecondenser 50, the capillary tube 60, the freezing chamber evaporator 30,the refrigerating chamber evaporator 40 and then the compressor 16, anda freezing cycle in the order of the compressor 16, the condenser 50,the capillary tube 60, the freezing chamber evaporator 30 and then thecompressor 16 are formed.

If it is desired to introduce the refrigerant having passed through thefreezing chamber evaporator 30 into the refrigerating chamber evaporator40, a refrigerant flow channel A of the 3-way valve 70 is opened and arefrigerant flow channel B is closed by turning the 3-way valve 70 on.Further, if it is desired to introduce the refrigerant having passedthrough the freezing chamber evaporator 30 into the compressor 16bypassing the refrigerating chamber evaporator 40, the refrigerant flowchannel A of the 3-way valve 70 is closed and the refrigerant flowchannel B is opened by turning the 3-way valve 70 off.

In the simultaneous freezing/refrigerating operation mode, a refrigerantin a gas phase compressed into a high-temperature and high-pressurestate by the compressor 16 of the refrigerator is introduced into thecondenser 50. The condenser 50 converts the refrigerant from the gasphase to a liquid phase by emitting heat to the outside through heatexchange with air at the outside of the refrigerator introduced by thecondenser fan 51. The refrigerant in the liquid phase having passedthrough the condenser 50 is decompressed via the capillary tube 60, andis then introduced sequentially into the freezing chamber evaporator 30and the refrigerating chamber evaporator 40. The freezing chamberevaporator 30 converts the refrigerant from the liquid phase to the gasphase by absorbing heat at the inside of the freezing chamber throughheat exchange with air at the inside of the refrigerator introduced bythe freezing chamber fan 31. Cool air is generated by such phaseconversion of the refrigerant, and the generated cool air is introducedinto the freezing chamber by the freezing chamber fan 31 and lowers thetemperature of the freezing chamber. Further, the refrigerating chamberevaporator 40 converts the refrigerant from the liquid phase to the gasphase by absorbing heat at the inside of the refrigerating chamberthrough heat exchange between with air at the inside of the refrigeratorintroduced by the refrigerating chamber fan 41. Cool air is generated bysuch phase conversion of the refrigerant, and the generated cool air isintroduced into the refrigerating chamber by the refrigerating chamberfan 41 and lowers the temperature of the refrigerating chamber. Therefrigerant having passed through the refrigerating chamber evaporator40 is introduced into the inlet side of the compressor 16.

On the other hand, in the freezing operation mode, a refrigerant in agas phase compressed into a high-temperature and high-pressure state bythe compressor 16 of the refrigerator is introduced into the condenser50. The condenser 50 converts the refrigerant from the gas phase to aliquid phase by emitting heat to the outside through heat exchange withair at the outside of the refrigerator introduced by the condenser fan51. The refrigerant in the liquid phase having passed through thecondenser 50 is decompressed via the capillary tube 60, and is thenintroduced into the freezing chamber evaporator 30. The freezing chamberevaporator 30 converts the refrigerant from the liquid phase to the gasphase by absorbing heat at the inside of the freezing chamber throughheat exchange with air at the inside of the refrigerator introduced bythe freezing chamber fan 31. Cool air is generated by such phaseconversion of the refrigerant, and the generated cool air is introducedinto the freezing chamber by the freezing chamber fan 31 and lowers thetemperature of the freezing chamber. The refrigerant having passedthrough the freezing chamber evaporator 30 is introduced into the inletside of the compressor 16.

The refrigerator having the above-described configuration includes anoperation control device 100 which increases evaporation latent heat ofthe refrigerant usable in the refrigerating chamber evaporator 40 in thesimultaneous freezing/refrigerating operation mode.

FIG. 3 is a control block diagram of the refrigerator in accordance withan embodiment of the present disclosure, FIG. 4 is a timing diagramillustrating rotational speed change of the freezing chamber fan in thefreezing operation mode and the simultaneous freezing/refrigeratingoperation mode of the refrigerator in accordance with an embodiment ofthe present disclosure, and FIG. 5 is a timing diagram illustratingrotational speed change of the compressor in the freezing operation modeand the simultaneous freezing/refrigerating operation mode of therefrigerator in accordance with an embodiment of the present disclosure.

As shown in FIG. 3, the operation control device 100 includes acontroller 110 which stores programs in the simultaneousfreezing/refrigerating operation mode and the freezing operation modeand thus outputs control signals to the respective components to coolboth the freezing chamber 12 and the refrigerating chamber 14 in thesimultaneous freezing/refrigerating operation mode and to cool thefreezing chamber 12 alone in the freezing operation mode.

Particularly, the controller 110 reduces evaporation latent heat of therefrigerant consumed by the freezing chamber evaporator 30 in thesimultaneous freezing/refrigerating operation mode and thus relativelyincreases evaporation latent heat of the refrigerant consumed by therefrigerating chamber evaporator 40. For this purpose, the controller110 changes the rotational speed of at least one of the freezing chamberfan 31 and/or the compressor 16 so as to increase evaporation latentheat of the refrigerant introduced into the refrigerating chamberevaporator 40.

As a control method of the freezing chamber fan 31, a method of reducingthe rotational speed of the freezing chamber fan 31 in the simultaneousfreezing/refrigerating operation mode or a method of stopping thefreezing chamber fan 31 for a designated time in the simultaneousfreezing/refrigerating operation mode may be used. These methods is torelatively increase evaporation latent heat usable in the refrigeratingchamber evaporator 40 by relatively reducing evaporation latent heatconsumed by the freezing chamber evaporator 30. Therethrough, coolingoperation of the refrigerating chamber may be performed withoutincreasing the amount of the refrigerant.

In addition to the control method of the freezing chamber fan 31, acontrol method of the rotational speed of an inverter compressor may beused. In such a method, the rotational speed of the compressor in thesimultaneous freezing/refrigerating operation is increased as comparedto the freezing operation, thereby exhibiting similar effects to thecontrol method of the freezing chamber fan 31. If the rotational speedof the compressor 16 in the simultaneous freezing/refrigeratingoperation is increased, the mass flow rate of the refrigerantcirculating in the cycle is increased at the same refrigerant chargingamount and thus evaporation latent heat of the refrigerant of arelatively larger amount may be used in the refrigerating chamberevaporator 40.

The freezing chamber temperature sensor 17 to sense the temperature ofthe freezing chamber 12 and the refrigerating chamber temperature sensor18 to sense the temperature of the refrigerating chamber 14 areelectrically connected to the input side of the controller 110.

Further, the compressor 16, the freezing chamber fan 31, therefrigerating chamber fan 41 and the condenser fan 51 operated bycontrol signals from the controller 110 are electrically connected tothe output side of the controller 110.

The controller 110 includes a fan speed control circuit 111 increasingand decreasing the rotational speed of the freezing chamber fan 31 and acompressor speed control circuit 112 increasing and decreasing therotational speed of the compressor 16.

The 3-way valve 70 operated by a control signal from the controller 110is electrically connected to the output side of the controller 110.

The above-described controller 110 performs one of the freezingoperation mode and the simultaneous freezing/refrigerating operationmode. The controller 110 opens or closes the respective refrigerant flowchannels A and B through the 3-way valve 70 in the freezing operationmode or the simultaneous freezing/refrigerating operation mode, therebyforming a freezing cycle or a freezing/refrigerating cycle.

As shown in FIG. 4, the controller 110 rotates the freezing chamber fan31 at a reference speed N1 in the freezing operation mode, and decreasesthe rotational speed of the freezing chamber fan 31 to a speed N2 whichis lower than the reference speed N1 in the simultaneousfreezing/refrigerating operation mode. Thereby, evaporation latent heatof the refrigerant consumed by the freezing chamber evaporator 30 in thesimultaneous freezing/refrigerating mode may be reduced, and thusevaporation latent heat of the refrigerant usable in the refrigerantchamber evaporator 40 may be relatively increased.

Further, the controller 110 operates the freezing chamber fan 31 for areference operation time in the freezing operation mode, and operatesthe freezing chamber fan 31 for a time shorter than the referenceoperation time in the freezing/refrigerating operation time. That is,the controller 110 forms a temporary stoppage section where the freezingchamber fan 31 is temporarily stopped in the simultaneousfreezing/refrigerating operation mode.

As shown in FIG. 5, the controller 110 rotates the compressor 16 at areference speed N1 in the freezing operation mode, and increases therotational speed of the compressor 16 to a speed N2 which is higher thanthe reference speed N1 in the simultaneous freezing/refrigeratingoperation mode. Thereby, evaporation latent heat of the refrigerantusable in the refrigerant chamber evaporator 40 in the simultaneousfreezing/refrigerating mode may be relatively increased.

FIG. 6 is a flowchart illustrating a control method of a refrigerator inaccordance with an embodiment of the present disclosure.

With reference to FIG. 6, the controller 110 first senses thetemperature of the freezing chamber 12, and determines whether or not afreezing operation condition is satisfied by comparing the sensedtemperature with a predetermined temperature (Operation 200).

As a result of the determination of Operation 200, if it is determinedthat the freezing operation condition is satisfied, the controller 110turns the compressor 16 on (Operation 202). At this time, the controller110 changes the refrigerant flow channel through the 3-way valve 70 sothat the refrigerant having passed through the freezing chamberevaporator 30 is introduced into the inlet side of the compressor 16.

After turning-on of the compressor 16, the controller 110 rotates thefreezing chamber fan 31 at a predetermined speed, i.e., a referencespeed FS_r (Operation 204).

After rotation of the freezing chamber fan 31, the controller 110determines whether or not a freezing operation off condition issatisfied (Operation 206).

As a result of the determination of Operation 206, if it is determinedthat the freezing operation off condition is satisfied, the controller110 turns the compressor 16 off (Operation 208) and turns the freezingchamber fan 31 off (Operation 210).

Thereafter, the controller 110 determines whether or not a simultaneousfreezing/refrigerating operation condition is satisfied (Operation 212).

As a result of the determination of Operation 212, if it is determinedthat the simultaneous freezing/refrigerating operation condition issatisfied, the controller 110 turns the compressor 16 on (Operation214). At this time, the controller 110 changes the refrigerant flowchannel through the 3-way valve 70 so that the refrigerant having passedthrough the freezing chamber evaporator 30 is introduced into the inletside of the compressor 16 via the refrigerating chamber evaporator 40.

After turning-on of the compressor 16, the controller 110 rotates thefreezing chamber fan 31 at a speed FS (FS<FS_r) which is lower than thepredetermined reference speed FS_r (Operation 216). At this time, thecontroller 110 operates the refrigerating chamber fan 41 at a referencespeed RS.

On the other hand, as the result of the determination of Operation 200,if it is determined that the freezing operation condition is notsatisfied, the controller 110 moves to Operation 212 and then performssubsequent Operations.

Further, as the result of the determination of Operation 212, if it isdetermined that the simultaneous freezing/refrigerating operationcondition is not satisfied, the controller 110 returns to thepredetermined routine.

FIG. 7 is a flowchart illustrating a control method of a refrigerator inaccordance with another embodiment of the present disclosure.

With reference to FIG. 7, the controller 110 first senses thetemperature of the freezing chamber 12, and determines whether or not afreezing operation condition is satisfied by comparing the sensedtemperature with a predetermined temperature (Operation 300).

As a result of the determination of Operation 300, if it is determinedthat the freezing operation condition is satisfied, the controller 110rotates the compressor 16 at a predetermined speed, i.e., a referencespeed CS_r (Operation 302). At this time, the controller 110 changes therefrigerant flow channel through the 3-way valve 70 so that therefrigerant having passed through the freezing chamber evaporator 30 isintroduced into the inlet side of the compressor 16.

After rotation of the compressor 16 at the predetermined reference speedCS_r, the controller 110 rotates the freezing chamber fan 31 at apredetermined speed, i.e., a reference speed FS_r (Operation 304).

After rotation of the freezing chamber fan 31 at the predeterminedreference speed FS_r, the controller 110 determines whether or not afreezing operation off condition is satisfied (Operation 306).

As a result of the determination of Operation 306, if it is determinedthat the freezing operation off condition is satisfied, the controller110 turns the compressor 16 off (Operation 308) and turns the freezingchamber fan 31 off (Operation 310).

Thereafter, the controller 110 determines whether or not a simultaneousfreezing/refrigerating operation condition is satisfied (Operation 312).

As a result of the determination of Operation 312, if it is determinedthat the simultaneous freezing/refrigerating operation condition issatisfied, the controller 110 rotates the compressor 16 at a speed CS(CS>CS_r) which is higher than the predetermined reference speed CS_r(Operation 314). At this time, the controller 110 changes therefrigerant flow channel through the 3-way valve 70 so that therefrigerant having passed through the freezing chamber evaporator 30 isintroduced into the inlet side of the compressor 16 via therefrigerating chamber evaporator 40.

After rotation of the compressor 16 at the speed CS, the controller 110rotates the freezing chamber fan 31 at the predetermined reference speedFS_r or a speed FS (FS<FS_r) which is lower than the predeterminedreference speed FS_r (Operation 316). At this time, the controller 110operates the refrigerating chamber fan 41 at a reference speed RS.

On the other hand, as the result of the determination of Operation 300,if it is determined that the freezing operation condition is notsatisfied, the controller 110 moves to Operation 312 and then performssubsequent Operations.

Further, as the result of the determination of Operation 312, if it isdetermined that the simultaneous freezing/refrigerating operationcondition is not satisfied, the controller 110 returns to thepredetermined routine.

In order to maximize effects of the NARM, the dryness and temperature ofthe refrigerant at the inlet of the evaporator need to be lowered, andfor this purpose, sub-coolers may be mounted. The sub-coolers lower thedryness of the refrigerant at the inlet of the freezing chamberevaporator 30 (the outlet of the capillary tube) through heat exchangebetween the refrigerant pipe at the outlet of the condenser 50 and therefrigerant pipe at the outlet of the refrigerating chamber evaporator40, and may thus lower the temperature of the refrigerant at the inletof the freezing chamber evaporator 30. The number and positions of thesub-coolers may be varied according to characteristics of the cycle, andfor example, two sub-coolers may be used.

A sub-cooler performing heat exchange between the low-pressure siderefrigerant pipe between the freezing chamber evaporator 30 and therefrigerating chamber evaporator 40 and the refrigerant pipe of thecondenser 50 is referred to as a low temperature heat exchanger (LTHX),and serves both to lower the temperature of the refrigerant at the inletof the freezing chamber evaporator and to raise a refrigerating chamberevaporation temperature. Since operation of the refrigerating chamber 14uses a part of evaporation latent heat of the refrigerant, the drynessof which is high, and the refrigerating chamber evaporation temperatureof the NARM becomes higher than that of a pure refrigerant. This reducesa heat exchange temperature difference between the refrigerant and air,thus reducing thermodynamic irreversible loss. Since the irreversibleloss is reduced in inverse proportion to the refrigerant chamberevaporation temperature, the LTHX may maximize reduction in theirreversible loss.

On the other hand, a sub-cooler performing heat exchange between theoutlet of the evaporator and the refrigerant pipe of the condenser isreferred to as a high temperature heat exchanger (HTHX). Such an HTHXserves to lower the temperature of the refrigerant at the inlet of theevaporator in the same manner as the LTHX.

As is apparent from the above description, a refrigerator in accordancewith an embodiment of the present disclosure reduces the rotationalspeed of a freezing chamber fan or stopping the freezing chamber fan fora designated time, and/or increasing the rotational speed of acompressor in a simultaneous freezing/refrigerating operation mode of anNARM cycle as compared to a freezing operation mode, and may thusdecrease evaporation latent heat of a refrigerant consumed by a freezingchamber evaporator and relatively increase evaporation latent heat ofthe refrigerant usable in a refrigerating chamber evaporator withoutincrease in a charging amount of the refrigerant, thereby preventingover-charging due to increase in the charging amount of the refrigerantand reducing cycling loss.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the disclosure, the scope of which is definedin the claims and their equivalents. For example, the technical featuresof the present disclosure may be applied to a direct coolingrefrigerator such as a KimChi refrigerator. In this case, the method ofcontrolling the rotational speed of the compressor as describe above maybe applied.

What is claimed is:
 1. A refrigerator comprising: a freezing chamber anda refrigerating chamber; a compressor to compress a refrigerant; arefrigerating chamber evaporator to cool the refrigerating chamber; afreezing chamber evaporator provided at an upstream position as comparedto a position of the refrigerating chamber evaporator, and to cool thefreezing chamber; a freezing chamber fan to blow cool air havingundergone heat exchange in the freezing chamber evaporator; and acontroller to control operations of the compressor and the freezingchamber fan, wherein the refrigerator has a freezing operation mode anda simultaneous freezing/refrigerating operation mode, and wherein thecontroller changes a rotational speed of at least one of the freezingchamber fan and the compressor so as to increase evaporation latent heatof the refrigerant introduced into the refrigerating chamber evaporatorin the simultaneous freezing/refrigerating operation mode as compared tothe freezing operation mode.
 2. The refrigerator according to claim 1,wherein the controller lowers the rotational speed of the freezingchamber fan in the simultaneous freezing/refrigerating operation mode ascompared to the freezing operation mode.
 3. The refrigerator accordingto claim 1, wherein the controller temporarily stops the rotationalspeed of the freezing chamber fan in the simultaneousfreezing/refrigerating operation mode.
 4. The refrigerator according toclaim 1, wherein the controller increases the rotational speed of thecompressor in the simultaneous freezing/refrigerating operation mode ascompared to a freezing operation mode.
 5. The refrigerator according toclaim 1, wherein the controller lowers the rotational speed of thefreezing chamber fan or temporarily stops the operation of the freezingchamber fan while increasing the rotational speed of the compressor inthe simultaneous freezing/refrigerating operation mode as compared tothe freezing operation mode.
 6. A control method of a refrigerator inwhich a freezing chamber evaporator is provided at an upstream positionas compared to a position of the refrigerating chamber evaporator, andhaving a freezing operation mode and a simultaneousfreezing/refrigerating operation mode, comprising: determining whetheror not the refrigerator operates in a simultaneousfreezing/refrigerating operation mode; and changing a rotational speedof at least one of a freezing chamber fan and a compressor so as toincrease evaporation latent heat of a refrigerant introduced into therefrigerating chamber evaporator, when the refrigerator operates in thesimultaneous freezing/refrigerating operation mode.
 7. The controlmethod according to claim 6, wherein the changing of the rotationalspeed of at least one of the freezing chamber fan and the compressorincludes lowering the rotational speed of the freezing chamber fan inthe simultaneous freezing/refrigerating operation mode as compared tothe freezing operation mode.
 8. The control method according to claim 6,wherein the changing of the rotational speed of at least one of thefreezing chamber fan and the compressor includes temporarily stoppingthe rotational speed of the freezing chamber fan in the simultaneousfreezing/refrigerating operation mode as compared to the freezingoperation mode.
 9. The control method according to claim 6, wherein thechanging of the rotational speed of at least one of the freezing chamberfan and the compressor includes increasing the rotational speed of thecompressor in the simultaneous freezing/refrigerating operation mode ascompared to the freezing operation mode.
 10. The control methodaccording to claim 6, wherein the changing of the rotational speed of atleast one of the freezing chamber fan and the compressor includeslowering the rotational speed of the freezing chamber fan or temporarilystopping the operation of the freezing chamber fan while increasing therotational speed of the compressor in the simultaneousfreezing/refrigerating operation mode as compared to the freezingoperation mode.
 11. The refrigerator according to claim 1, wherein therefrigerant is a non-azeotropic refrigerant mixture.
 12. The controlmethod according to claim 6, wherein the refrigerant is a non-azeotropicrefrigerant mixture.
 13. A refrigerator comprising: a compressor tocompress a refrigerant; a refrigerating chamber evaporator to cool therefrigerating chamber; a freezing chamber evaporator to cool thefreezing chamber, and provided at an upstream position than a positionof the refrigerating chamber evaporator; and a controller to control anoperation of the compressor, wherein the refrigerator has a freezingoperation mode and a simultaneous freezing/refrigerating operation mode,and the controller changes the rotational speed of the compressor so asto increase evaporation latent heat of the refrigerant introduced intothe refrigerating chamber evaporator in the simultaneousfreezing/refrigerating operation mode as compared to the freezingoperation mode.
 14. The refrigerator according to claim 13, wherein thecontroller increases the rotational speed of the compressor in thesimultaneous freezing/refrigerating operation mode as compared to thefreezing operation mode.
 15. The refrigerator according to claim 13,wherein the refrigerant is a non-azeotropic refrigerant mixture.
 16. Acontrol method of a refrigerator in which a freezing chamber evaporatoris provided at an upstream position than a position of the refrigeratingchamber evaporator, and having a freezing operation mode and asimultaneous freezing/refrigerating operation mode, comprising:determining whether the refrigerator operates in a simultaneousfreezing/refrigerating operation mode; and changing the rotational speedof a compressor as compared to the freezing operation mode so as toincrease evaporation latent heat of a refrigerant introduced into therefrigerating chamber evaporator when the refrigerator operates in thesimultaneous freezing/refrigerating operation mode.
 17. The controlmethod according to claim 16, wherein the changing of the rotationalspeed of the compressor includes increasing the rotational speed of thecompressor in the simultaneous freezing/refrigerating operation mode ascompared to the freezing operation mode.
 18. The control methodaccording to claim 16, wherein the refrigerant is a non-azeotropicrefrigerant mixture.